1. Field of the Invention
The present invention generally relates to heart pulsing means and, more particularly, to an improved myocardial lead.
2. Description of the Prior Art
The use of myocardial leads, in either bipolar or unipolar configurations, to stimulate the surface of a heart by the application of electric pulses is well known. Typically, a myocardial lead consists of an electrode from which a pin extends. The latter is inserted into the myocardium and the electrode is secured to the myocardium. The electrical pulses are supplied to the electrode pin from an appropriate source, typically a pacemaker, through a distal wire, which is connected at opposite ends to the electrode and the pacemaker.
A commercially available myocardial lead consists of an electrode in the form of a bent platinum rod, one end of which serves as the electrode pin. Connected to the other end of the platinum rod, by means of conductive epoxy, is one end of a distal wire. The other end of the distal wire, which is also of platinum, is connectable to a pacemaker. The advantages of using platinum as the electrode pin are well known. Briefly, platinum is biocompatible and furthermore is useful to pass electrical currents either anodially or cathodially into saline solutions, such as those present in the body without corrosion.
The particular prior art myocardial lead has a very significant disadvantage which greatly limits its life and its reliability. As is appreciated, due to heart motion and body movement the myocardial lead has to be able to withstand stress and bending without breaking. This is not attainable with platinum which when subjected to stress, such as a bending force, tends to break quite easily. Experience with the prior art myocardial lead has proven that either the bent platinum electrode and/or the platinum distal wire tend to break when subjected to stress forces, encountered due to heart and/or body motion. Any such break in the lead during use may be fatal to a patient, requiring reliable myocardial stimulation.